"Testing knowledge" aging test methods and standards for electronic products

Date：2022-04-29 13:52:25 Views：1835

During the processing of electronic products, due to the complex processing and extensive use of component materials, both processing defects and component defects can be divided into obvious defects and potential defects. Obvious defects refer to those defects that make the products unable to work normally, such as short circuit / open circuit, and the potential defects make the products temporarily usable, but the defects will be exposed soon during use, and the products cannot work normally. Potential defects cannot be found by conventional inspection methods, but eliminated by aging methods. If the effect of aging method is not good, the potential defects that have not been eliminated will eventually appear in the form of early failure (or failure) during product operation, resulting in an increase in product repair rate and maintenance cost.

What is aging test?

Burn in refers to the continuous application of environmental stress to components at a certain ambient temperature for a long time. Ess (environmental stress screen) includes not only high-temperature stress, but also many other stresses, such as temperature cycle, random vibration, etc. through the comprehensive action of electrical and thermal stress, it can accelerate various physical and chemical reaction processes inside components, Promote the early exposure of various potential defects hidden inside the components, so as to eliminate the early failure products.

Function of aging test

01 has a good screening effect for a series of defects that may exist in the process of manufacturing, such as surface contamination, poor lead welding, channel leakage, silicon wafer crack, oxide layer defect and local hot spot

02 for components without defects, aging can also promote the stability of their electrical parameters

The main items of aging test include:

Photoaging test

Light aging is the main aging damage of outdoor materials, and indoor materials will also be subject to a certain degree of light aging. The three main lamp sources of simulated light aging have their own advantages. Carbon arc lamp was first invented and used, and the measurement system was established earlier. Many Japanese standards and standards on fiber materials use carbon arc lamp. However, due to the high price and unstable performance of carbon arc lamp (the lamp tube needs to be replaced after 90 hours of use), it has been gradually replaced by xenon arc lamp and ultraviolet lamp. Xenon lamp has great advantages in simulating natural light, and the price is relatively low. It is suitable for most products

UV lamp produces light below 400nm, which can better accelerate the damage of UV to materials in simulated natural light. The acceleration factor is higher than that of xenon lamp, and the stability of light source is better than that of xenon lamp, but it is easy to cause damage to the output of unnatural light (especially UVB lamp)

Main application scope: Rubber and plastic, coating and ink products for outdoor and indoor use, equipment shells such as communication and electrical appliances, auto parts and motorcycle accessories.

Main reference standards: GB / T 7141, ASTM D3045, JIS K 6257, etc.

The thermal aging box has the program function, which can set the temperature change through the program, which is suitable for the thermal aging needs of various products.

Main application scope: heat aging test of various products, such as PCB board, insulating rubber in electrical appliances, products with long service life demand (such as jacket material for stay cable bridge, the service life should be more than 20 years), etc. to investigate the change of product performance and the reliability of products with the passage of service time.

Damp heat aging

Main reference standards: general standards include GB / T 15905, GB / T 2573, etc.

In addition, the change curve of humidity and temperature can be set according to different product standards and enterprise standards, which is suitable for various complex damp heat aging tests. During the use of the product, it is easy to be affected by temperature and humidity. For some water sensitive materials, such as pet and PBT, it is necessary to carry out damp heat aging test to evaluate whether it is suitable for long-term use in humid environment.

Salt fog aging

Main reference standards: GB / T 10125, GB / T 12000 \, ASTM d117, jisz2371 and other standards.

Conduct neutral salt spray, acid salt spray and copper ion accelerated salt spray test. It is mainly used to simulate the corrosion of sodium chloride dissolved in water vapor in the atmosphere on coatings, coatings and other protective layers as well as metal ground materials, especially in coastal areas and areas around inland salt lakes. The salt in the air is high, and the products are easy to be corroded by salt spray.

Main applicable products: all kinds of coatings, such as architectural exterior wall coatings, marine coatings, container coatings, and all kinds of coatings.

Ozone aging

Main reference standards: GB / T 7762, GB / T 24134, GB / T 13642, Hg / T 2869, JIS K 6259, ASTM D 1149.

Mainly investigate the ozone resistance of rubber (rubber contains a large number of double bonds, which is vulnerable to ozone attack, especially in dynamic use or stretching, the damage of ozone to rubber is more serious), and also investigate the ozone resistance of TPU, EPDM and other new elastomers.

High and low temperature cycle

Main reference standards: GB / T 2423, JG / T 25 determination method of freeze-thaw cycle resistance of architectural coatings and other standards. The test can be carried out according to the relevant test methods of high and low temperature cycle and freeze-thaw cycle in different product standards.

It is mainly used for testing building coatings and equipment used in special environment.

Precautions for aging test

In order to achieve satisfactory aging effect, the following points should be paid attention to:

01 aging equipment shall be provided with good measures to prevent self-excited oscillation

02 when applying voltage to the device, it should be increased slowly from zero and decreased slowly when removing the voltage, otherwise the instantaneous pulse generated by the sudden change of power supply voltage may damage the device. After aging, it shall be measured in time within the time specified in the standard or specification, otherwise some out of tolerance parameters during aging will return to the original value

03 in order to ensure that the transistor can age at the highest temperature, the thermal resistance of the transistor should be measured accurately

For integrated circuits, because their working voltage and current are greatly limited, their junction temperature rise is very small. It is difficult to reach the temperature required for effective aging without increasing the ambient temperature. Therefore, normal temperature static power aging is only applied in some integrated circuits (linear circuits and digital circuits).